JP2023100867A - Electrode tab, battery, and method for mounting electrode tab - Google Patents

Abstract

To provide an electrode tab capable of ensuring sufficient air tightness of a secondary battery even if the thickness of an electrode tab is increased to some extent.SOLUTION: An electrode tab can be mounted to a housing body for housing a battery element therein, and is configured to be electrically connected to an electrode of the battery element. The electrode tab includes a mounting portion configured to be mounted on the housing body. In a cross section of the mounting portion, the thickness of a central portion in the width direction is thicker than the thickness of an edge portion in the width direction. In the cross section of the mounting portion, a curve connecting at least a part between any point that corresponds to the central portion on an outer periphery and any point that corresponds to the edge portion on the outer periphery has at least one inflection point.SELECTED DRAWING: Figure 3

Description

The present invention relates to electrode tabs, batteries, and methods of attaching electrode tabs.

Japanese Patent Laying-Open No. 2014-207069 (Patent Document 1) discloses an electrode tab used in a laminated lithium ion battery. The cross-sectional shape of this electrode tab is a shape in which both ends in the width direction are chamfered. According to this electrode tab, since the resin smoothly flows to the side surface of the electrode tab when the laminate film and the electrode tab are heat-sealed with the resin interposed therebetween, it is possible to obtain good airtightness in the completed laminated lithium ion battery. (See Patent Document 1).

JP 2014-207069 A

Among secondary batteries such as lithium-ion batteries and other primary batteries, there are batteries of a type in which electrode tabs protrude outward from a container housing a battery element therein. In such batteries, generally, the greater the maximum input/output power of a secondary battery or the maximum output power of a primary battery, the thicker the electrode tabs used in these batteries. Depending on the thickness of the electrode tab, the electrode tab disclosed in Patent Document 1 may not be able to sufficiently secure the airtightness of the battery.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and an object of the present invention is to provide an electrode that can sufficiently ensure the airtightness of a battery even if the thickness of the electrode tab is increased to some extent. is to provide tabs.

An electrode tab according to one aspect of the invention is attachable to a container housing a battery element and is configured to be electrically connected to an electrode of the battery element. The electrode tab includes an attachment portion configured to attach to the housing. In the cross section of the mounting portion, the widthwise central portion is thicker than the widthwise end portions. In the cross section of the mounting portion, a curve connecting at least a portion between any point on the outer circumference corresponding to the central portion and any point on the outer circumference corresponding to the end portion has at least one variation. has an inflection point.

If the width direction edge of the electrode tab suddenly becomes thinner (if a large step is formed), sufficient adhesion may not be achieved at that position, and the airtightness of the secondary battery may decrease. In the electrode tab according to the present invention, in the cross section of the attachment portion, at least a portion between any point on the outer circumference corresponding to the central portion and any point on the outer circumference corresponding to the end portion is The connecting curves have at least one inflection point. That is, in the cross section of the attachment portion of the electrode tab, the cross-sectional thickness is large and smoothly reduced in the central region, and the cross-sectional thickness is small and smoothly reduced in the end region. Therefore, according to this electrode tab, since the thickness of the electrode tab does not suddenly decrease at the widthwise end of the electrode tab, even if the thickness of the electrode tab increases to some extent, the electrode tab can be sufficiently adhered to the container. , the airtightness of the battery can be sufficiently ensured.

In the electrode tab, the containing body may be in the form of a pouch, and the mounting portion may be configured to be attached to the containing body while being sandwiched between the containing bodies.

In the electrode tab, an adhesive member may be adhered to the surface of the attachment portion.

According to this electrode tab, it is possible to easily bond the container and the electrode tab.

A battery according to another aspect of the present invention includes a battery element, a container, and the electrode tab. The container accommodates the battery element. The electrode tabs are attached to the container and electrically connected to the electrodes of the battery element. A concave portion recessed toward the mounting portion is formed on the surface of the container at the position where the container is attached to the mounting portion.

In this battery, a concave portion recessed toward the mounting portion is formed on the surface of the container at the position where the mounting portion is mounted. That is, in this battery, the surface of the containing body where it is attached to the mounting portion is pressed, and the containing body and the electrode tab are joined more firmly. Therefore, according to this battery, the airtightness of the battery can be further improved.

In the battery described above, an adhesive layer may be formed between the mounting portion and the container.

In the above battery, the adhesive layer may be a film-like adhesive member.

A method of attaching an electrode tab according to another aspect of the present invention includes the steps of sandwiching the attachment portion of the electrode tab between containers, and heat-sealing regions of the container sandwiching the electrode tab.

In this attachment method, the electrode tabs attached to the container connect any point on the outer periphery corresponding to the center portion and any point on the outer periphery corresponding to the end portions in the cross section of the attachment portion. A curve has at least one inflection point. Therefore, according to this method of attaching the electrode tabs, the thickness of the electrode tabs does not suddenly decrease at the ends in the width direction. can be secured.

The method for attaching the electrode tab may further include forming a concave portion recessed toward the attachment portion on the surface of the container at the position attached to the attachment portion.

That is, in this method of attaching the electrode tabs, the surface of the container where it is attached to the attachment portion is pressed, so that the container and the electrode tab are joined more firmly. Therefore, according to this electrode tab attachment method, the airtightness of the battery can be further enhanced.

ADVANTAGE OF THE INVENTION According to this invention, the electrode tab which can fully ensure the airtightness of a battery even if the thickness of an electrode tab becomes thick to some extent can be provided.

It is a top view of a battery. It is a top view of an electrode tab. 3 is a cross-sectional view taken along line III-III of FIG. 2; FIG. FIG. 4 is a plan view of the electrode tabs attached to the container; FIG. 5 is a cross-sectional view taken along line VV of FIG. 4; It is a flowchart which shows the manufacturing procedure of an electrode tab. 4 is a flow chart showing a procedure for attaching an electrode tab to a container; FIG. 10 is a diagram showing a cross-sectional shape of an attachment portion of an electrode tab in Modification 1; FIG. 10 is a diagram showing a cross-sectional shape of an attachment portion of an electrode tab in Modification 2; FIG. 11 is a diagram showing a cross-sectional shape of an attachment portion of an electrode tab in Modification 3;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

[1. overview]
FIG. 1 is a plan view of battery 10 including electrode tab 100 according to the present embodiment. As shown in FIG. 1, the battery 10 includes a battery element 300, a pouch-like container 200, and electrode tabs 100 (100A, 100B).

The battery element 300 is a power storage member such as a lithium ion battery, a capacitor, or an all solid state battery.

The pouch-shaped container 200 is configured by a laminate (laminate film) having, for example, a substrate layer, a barrier layer, and a heat-fusible resin layer in this order. For example, the container 200 is composed of two sheets of laminated films, and the peripheral edges (sealed portions 210) of the stacked laminated films are heat-sealed. The housing body 200 is configured to house the battery element 300 inside while sandwiching the electrode tabs 100A and 100B at the periphery.

Electrode tabs 100 ( 100 A, 100 B) are metal terminals used for power input/output in battery element 300 . One end of each electrode tab 100 is electrically connected to the electrode (positive electrode or negative electrode) of the battery element 300 , and the other end protrudes outward from the edge of the container 200 .

A metal material forming the electrode tab 100 is, for example, aluminum, nickel, copper, or the like. For example, when the battery element 300 is a lithium ion battery, the electrode tab 100 connected to the positive electrode is usually made of aluminum or the like, and the electrode tab 100 connected to the negative electrode is usually made of copper, nickel or the like. be. Furthermore, the surface of the electrode tab 100 made of these metal materials can be subjected to surface treatment such as providing an easy-adhesion layer. This is for firmly attaching an adhesive film 120 (FIGS. 2 and 3), which will be described later, to the surface of the electrode tab main body 110, and by using the same resin as the outermost layer of the adhesive film 120 for the easy-adhesion layer. It becomes possible. In order to firmly attach the adhesive film 120 to the surface of the electrode tab body 110, the surface of the electrode tab body 110 may be roughened.

In general, as the maximum input/output power of a secondary battery increases, the thickness of electrode tabs used in the secondary battery increases. If the thickness of the electrode tab is large, when the container is heat-sealed with the electrode tab sandwiched therebetween, the space between the electrode tab and the container is not sufficiently filled with resin, and a gap is likely to form. That is, when the thickness of the electrode tab is large, it is difficult to sufficiently secure the airtightness of the secondary battery.

In electrode tab 100 according to the present embodiment, the cross-sectional shape of electrode tab 100 is devised in order to ensure sufficient airtightness of battery 10 even when electrode tab 100 is thick. Hereinafter, the configuration of the electrode tab 100, the mounting state of the electrode tab 100 to the container 200, the manufacturing method of the electrode tab 100, and the mounting method of the electrode tab 100 to the container 200 will be described in order.

[2. Configuration of electrode tab]
FIG. 2 is a plan view of the electrode tab 100. FIG. As shown in FIG. 2, electrode tab 100 includes electrode tab body 110 and adhesive film 120 . That is, in the electrode tab 100, the adhesive film 120 is attached to the electrode tab main body 110 in advance. The electrode tab body 110 includes an attachment portion 112 , a wiring connection portion 114 and an electrode connection portion 116 . Attachment portion 112 is the area to which adhesive film 120 is attached. The wiring connection portion 114 is an area for connecting wiring connected to the load. The electrode connection portion 116 is a region for connecting electrodes of the battery element 300 .

Adhesive film 120 is configured to adhere to both electrode tab body 110 and container 200 (FIG. 1) by heat sealing. As the adhesive film 120, various known adhesive films can be adopted. As an example, the adhesive film 120 may be a single layer film of maleic anhydride-modified polypropylene (PPa), or a laminated film of PPa, polyethylene naphthalate (PEN) and PPa. Also, in place of the above PPa resin, a resin that can adhere to metals such as ionomer resin, modified polyethylene, and EVA can be applied.

In this embodiment, as the adhesive film 120, a laminate film having a three-layer structure including a core material, which is composed of PPa/PEN (core material)/PPa, is employed. As the core material, various known materials other than PEN can be used. As an example, the core material may be polyester fiber, polyamide fiber, or carbon fiber. The reason why the core material is included in the adhesive film 120 will be described later in detail.

The adhesive film 120 is adhered to the electrode tab main body 110 while covering the outer periphery of the mounting portion 112 of the electrode tab main body 110 as described above. Since the adhesive film 120 also adheres to the housing body 200 (FIG. 1), the metal electrode tab 100 and the housing body 200 can be easily adhered by heat sealing according to the electrode tab 100 .

Further, the widthwise length W1 of the adhesive film 120 is longer than the widthwise length W2 of the attachment portion 112 . In other words, in the electrode tab 100 , the adhesive film 120 extends over one or more circumferences of the attachment portion 112 . Therefore, according to the electrode tab 100, since the adhesive film 120 can be arranged in a wide range, the adhesion between the electrode tab 100 and the container 200 can be made more reliable.

FIG. 3 is a cross-sectional view taken along line III-III of FIG. As shown in FIG. 3, the cross section of the mounting portion 112 of the electrode tab 100 has a curved shape all around. The cross-section of the mounting portion 112 includes a circular portion 102 and wings 104 and 106 .

In the cross section of the mounting portion 112, the widthwise central portion (thickness of the circular portion 102) is thicker than the widthwise end portion (thickness at the tips of the wing-shaped extension portions 104 and 106).

Further, in the cross section of the mounting portion 112, a curve connecting a point P1 on the outer periphery corresponding to the central portion in the width direction and a point P3 on the outer periphery corresponding to the end portions in the width direction is an inflection point P5, has P6. A curve connecting a point P1 on the outer circumference corresponding to the central portion in the width direction and a point P4 on the outer circumference corresponding to the end portions in the width direction has inflection points P7 and P8. A curve connecting a point P2 on the outer periphery corresponding to the central portion in the width direction and a point P3 on the outer periphery corresponding to the end portions in the width direction has inflection points P9 and P10. A curve connecting a point P2 on the outer circumference corresponding to the central portion in the width direction and a point P4 on the outer circumference corresponding to the end portions in the width direction has inflection points P11 and P12. The “central portion” in the width direction in the cross section of the mounting portion 112 indicates the center in the width direction in the cross section of the mounting portion 112 (for example, the region between the points P1 and P2), and the cross section of the mounting portion 112 The “ends” in the width direction in FIG.

If the width direction edge of the electrode tab suddenly becomes thinner (if a large step is formed), sufficient adhesion may not be achieved at that position, and the airtightness of the secondary battery may decrease. In the electrode tab 100, in the cross section of the attachment portion 112, any point (points P1, P2) on the outer periphery corresponding to the central portion in the width direction and any point on the outer periphery corresponding to the end portions in the width direction. A curve connecting at least a part between the points (points P3, P4) has at least one inflection point (inflection points P5, P6, P7, P8, P9, P10, P11, P12).

That is, in the cross section of the attachment portion 112 of the electrode tab 100, the cross-sectional thickness is large and smoothly reduced in the central region, and the cross-sectional thickness is small and smoothly reduced in the end region. Also, the area near the center and the area near the end are smoothly connected. Therefore, according to the electrode tab 100, the thickness of the electrode tab 100 does not suddenly decrease at the widthwise end of the electrode tab 100, and each region is smoothly connected, so that the thickness of the electrode tab 100 increases to some extent. However, the electrode tab 100 can be sufficiently adhered to the container 200, and the airtightness of the battery 10 can be sufficiently ensured.

The cross-sectional shapes of the wiring connection portion 114 and the electrode connection portion 116 may be the same as or different from the cross-sectional shape of the mounting portion 112 .

[3. Mounting state of the electrode tab]
FIG. 4 is a plan view of the electrode tab 100 attached to the container 200. FIG. 5 is a cross-sectional view taken along the line VV of FIG. 4. FIG. As shown in FIGS. 4 and 5, in the container 200, the sealing portion 210 is heat-sealed with the electrode tab 100 sandwiched therebetween. Although the details will be described later, the seal portion 210 is adhered by the first heat seal.

Furthermore, a concave portion 212 recessed toward the mounting portion 112 is formed on the surface of the seal portion 210 at a position corresponding to the upper portion of the mounting portion 112 of the electrode tab 100 . The recess 212 is formed by the second heat sealing. That is, in battery 10 , the surface of container 200 attached to mounting portion 112 is pressed, and container 200 and electrode tab 100 are joined more firmly. Therefore, according to this battery 10, the airtightness of the battery 10 can be further improved.

Moreover, as described above, the adhesive film 120 in the electrode tab 100 contains a core material. If the adhesive film 120 does not contain a core material, if the heat sealing is repeated (for example, twice), the heat and pressure cause the adhesiveness of the heat-sealable resin layer constituting the inner layer of the container 200 to deteriorate. The film can melt and extrude into areas of weaker pressure. As a result, a metal foil layer such as an aluminum foil constituting a barrier layer of the container 200 and the electrode tab main body 110 are short-circuited, and an insulating layer (container The heat-sealable resin layer and the adhesive film forming the inner layer of the container 200 may be destroyed, and a short circuit may occur in the container 200 . In electrode tab 100 according to the present embodiment, adhesive film 120 contains a core material. Therefore, according to this electrode tab 100, since the adhesive film 120 containing the core material suppresses the breakage of the insulating layer, even if heat sealing is performed twice (multiple times) near the electrode tab 100, , the insulation in the container 200 can be maintained.

[4. Manufacturing method of electrode tab]
FIG. 6 is a flow chart showing the manufacturing procedure of the electrode tab 100. As shown in FIG. The processing shown in this flow chart is executed by, for example, a manufacturing apparatus with the electrode tab body 110 and the adhesive film 120 prepared.

Referring to FIG. 6, the manufacturing apparatus sandwiches attachment portion 112 of electrode tab main body 110 with adhesive film 120 (step S100). The manufacturing apparatus heat seals the adhesive film 120 to the mounting portion 112 while the mounting portion 112 is sandwiched between the adhesive films 120 (step S110). Thereby, the electrode tab 100 is completed. The effect of attaching the adhesive film 120 to the electrode tab main body 110 by heat-sealing in advance is as follows. When the electrode tab main body 110 is made of thick metal, even if only one portion, specifically, the attachment portion 112 which is a part of the electrode tab main body 110 is heat-sealed and heated, heat is transferred to portions other than the attachment portion 112 . Heat is transferred to the entire surface and dissipates from the metal surface that is not in contact with the seal bar. Therefore, rather than heat-sealing the electrode tab body 110 and the adhesive film 120 at the same time when the container 200 is heat-sealed, it is more preferable to heat-seal the adhesive film 120 to the electrode tab body 110 in advance. It is possible to stably adhere the adhesive film 120 to the electrode tab main body 110 .

[5. How to attach the electrode tab]
FIG. 7 is a flow chart showing the procedure for attaching the electrode tab 100 to the container 200. As shown in FIG. The processing shown in this flow chart is executed by, for example, a manufacturing apparatus with the electrode tab 100 and the container 200 prepared.

Referring to FIG. 7, the manufacturing apparatus places electrode tab 100 on container 200 (step S200). For example, the manufacturing apparatus places the electrode tabs 100 on the container 200 so that the electrode tabs 100 are sandwiched between the peripheral edges of the container 200 . In this state, one end of electrode tab 100 is connected to the electrode of battery element 300 .

The manufacturing apparatus performs the first heat sealing (primary heat sealing) while the electrode tab 100 is sandwiched between the peripheral edges of the container 200 (step S210). As a result, the entire periphery of the container 200 is heat-sealed. After that, the manufacturing apparatus performs a second heat seal (secondary heat seal) to strengthen the seal around the electrode tab 100 (step S220). As a result, the periphery (recess 212) of the electrode tab 100 is heat-sealed more firmly. Thereby, the electrode tab 100 is attached to the container 200 .

[6. feature]
As described above, in electrode tab 100 according to the present embodiment, in the cross section of attachment portion 112, any point (points P1, P2) on the outer circumference corresponding to the central portion in the width direction and the end in the width direction A curve connecting at least a part of any point (points P3, P4) on the outer circumference corresponding to the part has at least one inflection point (inflection points P5, P6, P7, P8, P9, P10, P11, P12).

That is, in the cross section of the attachment portion 112 of the electrode tab 100, the cross-sectional thickness is large and smoothly reduced in the central region, and the cross-sectional thickness is small and smoothly reduced in the end region. Also, the area near the center and the area near the end are smoothly connected. Therefore, according to the electrode tab 100, the thickness of the electrode tab 100 does not suddenly decrease at the widthwise end of the electrode tab 100, and each region is smoothly connected, so that the thickness of the electrode tab 100 increases to some extent. However, the electrode tab 100 can be sufficiently adhered to the container 200, and the airtightness of the battery 10 can be sufficiently ensured.

[7. Modification]
Although the embodiments have been described above, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the scope of the invention. Modifications will be described below.

<7-1>
In the above embodiment, the cross-sectional shape of the mounting portion 112 was the shape shown in FIG. However, the cross-sectional shape of the mounting portion 112 is not limited to the shape shown in FIG. For example, the cross-sectional shape of the mounting portion 112 may be a shape such as the following modified example 1-3.

FIG. 8 is a diagram showing a cross-sectional shape of the mounting portion 112A of the electrode tab 100A in Modification 1. As shown in FIG. As shown in FIG. 8, the cross-sectional shape of the mounting portion connects, for example, a point P1A on the outer periphery corresponding to the central portion in the width direction and a point P4A on the outer periphery corresponding to the end portions in the width direction. A curve may have only one inflection point P7A.

FIG. 9 is a diagram showing a cross-sectional shape of an attachment portion 112B of an electrode tab 100B in Modification 2. As shown in FIG. As shown in FIG. 9, the cross-sectional shape of the mounting portion is such that, for example, a flat portion 117 is formed between a point on the outer circumference corresponding to the center in the width direction and a point on the outer circumference corresponding to the end in the width direction. , 118 may be included.

Also, FIG. 10 is a diagram showing a cross-sectional shape of an attachment portion 112C of an electrode tab 100C in Modification 3. As shown in FIG. As shown in FIG. 10, the cross-sectional shape of the mounting portion is such that a curve connecting points on the outer circumference corresponding to the central portion in the width direction and points on the outer circumference corresponding to the ends in the width direction is formed. Even if it has only one point of inflection and includes a flat portion between a point on the outer circumference corresponding to the central portion in the width direction and a point on the outer circumference corresponding to the end portion in the width direction. good.

<7-2>
Further, in electrode tab 100 according to the above-described embodiment, adhesive film 120 is adhered to electrode tab body 110 in advance. However, the adhesive film 120 does not necessarily have to be adhered to the electrode tab body 110 in advance. For example, the adhesive film 120 may be sandwiched between the electrode tab 100 and the container 200 for the first time when the electrode tab 100 and the container 200 are heat-sealed.

<7-3>
Further, in electrode tab 100 according to the above embodiment, adhesive film 120 is adhered to electrode tab main body 110 . However, the adhesive member adhered to the electrode tab body 110 is not limited to the adhesive film 120 . For example, only an adhesive resin layer may be formed on the surface of attachment portion 112 of electrode tab main body 110 .

<7-4>
Moreover, in the above-described embodiment, heat sealing was performed twice in order to attach the electrode tab 100 to the container 200 . However, heat sealing need not necessarily be performed twice. For example, heat sealing may be performed only once to adhere the seal portion 210 .

<7-5>
In addition, in the cross section of the attachment portion 112 of the electrode tab 100 according to the above-described embodiment, any point on the outer circumference corresponding to the central portion in the width direction and any point on the outer circumference corresponding to the end portion in the width direction The curve connecting between the points had two inflection points. However, the number of inflection points included in the curve is not limited to two. The number of inflection points included in the curve may be one, as described above, or three or more.

<7-6>
In the above embodiment, adhesive film 120 includes a core material. However, the adhesive film 120 does not necessarily have to contain a core material.

<7-7>
In the above embodiment, electrode tabs 100A and 100B were arranged on opposite sides of battery 10 . However, the arrangement locations of the electrode tabs 100A and 100B are not limited to this. For example, electrode tabs 100A and 100B may be arranged on the same side of battery 10 .

10 Battery 100, 100A, 100B, 100C Electrode tab 102 Circular part 104, 106 Wing-shaped extension 110 Electrode tab body 112, 112A, 112B Mounting part 114 Wiring connection part 116 Electrode connection part 117, 118 flat portion, 120 adhesive film, 200 container, 210 sealing portion, 212 concave portion, 300 battery element.

Claims (1)

An electrode tab attachable to a container housing a battery element and configured to be electrically connected to an electrode of the battery element,
a mounting portion configured to be attached to the container;
In the cross section of the mounting portion, the widthwise central portion is thicker than the widthwise end portions,
In the cross section, a curve connecting at least a portion between any point on the outer periphery corresponding to the central portion and any point on the outer periphery corresponding to the end portion has at least one inflection point. electrode tabs.